#define _CRT_SECURE_WARNINGS 520
#include<stdio.h>
int main()
{
	int the_num_nine = 0;
	for (int i = 9; i <= 99; i++)
	{
		int temp = i;
		while (temp > 0)
		{
			if (temp % 10 == 9)
				the_num_nine++;
			temp /= 10;
		}
	}
	printf("%d", the_num_nine);
	return 0;
}

